Most of the time, checked exceptions remain an unused language feature, because:

  A.) String to Integer with null handling 
      for HTTP GET/POST transformation isn't
      worth the effort, because you're users
      are drunk idiots, and they won't 
      pay attention to your carefully stratified
      error messages anyway. So just tell them
      to sober up, straighten out, and fly 
      right, and barf a hideous, uninformative 
      stack trace at them to scare them off
      until they go away, and come back in
      the morning.

  B.) Developers are so rushed to just get shit
      done that NullPointerExceptions, 
      NumberFormatExceptions, 
      ArrayIndexOutOfBoundsExceptions and so
      forth, are useful enough, and probably
      don't need much more differentiation
      anyway. As middleware developers, we're
      really not dealing with anything too
      exotic, and so we mostly don't need to
      re-interpret things like sensor or transducer
      state, or spin dial knob rotation angle,
      or leaf spring load, or magnetic flux.

So, just because 90% of server side web developers don't use it, doesn't mean it's a failure. It just means that interpreting discete character data from noodniks on the other side of a keyboard and pointing device, behind a TCP/IP connection can only get so complicated.